For which one of the following compounds standard enthalpy change (∆H∘) can be measured directly by calorimeter?
Correct answer: D. MgO
- A. CCI4
- B. Al2O3
- C. B2O3
- D. MgO
Explanation
Option D, MgO (magnesium oxide), is correct because its standard enthalpy change (∆H∘) can be measured directly by a calorimeter.Calorimetry is a technique used to measure the heat absorbed or released during a chemical or physical process. In the case of MgO, it is formed from its elements, magnesium (Mg) and oxygen (O2), through a chemical reaction:2Mg(s) + O2(g) ⟶ 2MgO(s)The heat released during this reaction can be measured directly using a calorimeter. The calorimeter allows for the precise measurement of the temperature change that occurs during the reaction, which is directly related to the enthalpy change (∆H∘) of the reaction.Options A, B, and C are incorrect because the standard enthalpy change of formation (∆H∘f) for these compounds involves reactions that are not as straightforward or easily measurable using a calorimeter.
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About Thermochemistry and Energetics of Chemical Reactions
Thermochemistry measures energy changes in chemical reactions and distinguishes exothermic from endothermic processes. Work covers systems, surroundings and state functions, internal energy, the first law of thermodynamics, enthalpy and Hess's law, including the sign conventions used when heat enters or leaves a system.
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